The present invention relates to a process for the direct carbonylation of C--H bonds of hydrocarbons for the production of aldehydes and/or other useful products such as olefins, alcohols, carboxylic acids, ketones, and so forth.
In principle, various useful products such as aldehydes, carboxylic acids, alcohols, ketones and olefins can be produced by directly functionalizing hydrocarbons. In particular, the direct and selective carbonylation of hydrocarbons under mild conditions is of great interest. Although a carbon-to-hydrogen bond of the hydrocarbons must be activated in the carbonylation, the bond energy of the carbon-to-hydrogen bond is high and, therefore the direct carbonylation is thought to be quite difficult. In fact, a process for directly carbonylating hydrocarbons with carbon monoxide in the presence of a metal-complex has substantially been unknown.
An indirect carbonylation process has been employed heretofore which comprises converting a hydrocarbon into an activated compound by oxidation or halogenation, and reacting the compound with carbon monoxide in the presence of a hydrogen source or a nucleophilic reagent. However, the number of the steps of such an indirect carbonylation process is larger than that of the direct carbonylation process, so that the indirect process is not preferred from the viewpoint of saving resources and energy.
On the other hand, complex catalysts are studied recently and investigations are made for the purpose of employing a combination of a complex catalyst with other activation processes for the reaction. In particular, intensive investigations of a combination of the activation by light and a metal-complex are in progress. However, any efficient direct carbonylation processes wherein a hydrocarbon is reacted with carbon monoxide in the presence of a complex catalyst under irradiation with light have not been known yet.
R. Eisenberg et al have made reports on photochemical carbonylation of benzene in the presence of rhodium complex or iridium complex (Organometallics, 1983, 2, 767 and J. Am. Chem. Soc. 1986, 108, 535). According to the reports, the yield attained is extremely low, and since the low yields are due to a thermodynamic limitation, it essentially is difficult to attain an improvement in or relating to the yield. Further, the reports are limited to deal only with reactions of benzene, and in the prior art there is not known an instance of the reaction of olefines.